Tongue weight? wouldn't this be much like a boat trailer with a small block on the transom? (weight is probably less on the boat)But......
We pulled are single axle boat trailer all over the state as a kid with a Olds Delta 88 seem to work ,kinda were I'm coming from.

I'm not trying to argue but seems like it would be better all the way around if the motor is not working as hard its not building heat in the tranny or burning as much fuel to get the work done it would save [shrug].

Well I appreciate everyones input, thats what I wanted .I'm going to do some more research and probably build one, we will see what happens might just be a big pile of crap........................
Thanks Jeff

My personal experience is that towing my sand rail on its T-trailer, which was the same weight as my old 14 ft flatbed tandem.

The sand rail I didn't feel behind the truck and it didn't really affect the mileage at all. Even empty, I could feel the bigger trailer and it knocked a mpg off the truck.

I think its a combination of these things:

Less weight. With a LIGHTWEIGHT wheeling rig, this can be 15-20% reduction of weight, which isn't insignificant.

Lower profile. I think designed right, you could lower the towed vehicle 8" or so over a standard trailer and 12+" over a deckover. Wind resistance is a significant portion of what is sucking down your gas.

Less road drag: Single axle instead of two axles. No scrubbing turns, 1/2 the rolling resistance.

I bet you coudl gain 0.5-1mpg, and have a smaller feeling trailer with this setup.

BTW, to answer your original question, I think its OK to not have springs on the trailer, if you strap down your axles, not the body. At least with standard springs and shocks. I'd watch your shocks, though. Don't know if I'd do it with air shocks. I've had my Toyotas shocks leak and get hot while on the trailer, on a really bumpy road.,...

Personally, I've had the same ideas in my head for a while in regards to my next future project. Build a trailer specifically for the vehicle, balanced perfectly, keep it as low as possible. Dedicated trailer for use as storage of the vehicle too.

My next project is going to be some tiny something. I want to have the ability to tow it with a Jeep or Yukon and not have the whole thing weight more than a big pop-up camper.

If you can net another 1-2mpg+, each long trip to go wheeling, it could save you hundreds of dollars. And if you didn't need that 3/4ton anymore, then your DD'ing mpg could go way up because you don't need the big engine anymore.

I would still want suspension on the trailer and I wouldn't want a dually setup.

Its cool to see all the different ideas. If the majority of your towing will be at highway speeds, then, as others have already said, aerodynamics will have a much greater impact than anything else. Since everything consists of engineering compromises, make reducing drag a priority over reducing weight.

The security of four tires is nice and the dual wheel setup appears to be a good alternative to a tandem axle setup. Anybody have thoughts why dualys wouldnít be a good compromise?

Springs or no springs? With no springs the unsprung weight will be huge. Hit a large bump and without springs to absorb the impact energy you will see much higher peak loads and stresses to the trailer structure. Remember you will have to add the trail rigís unsprung weight (tires, rims, axles, and parts of the suspension) to the trailer weight to get the total unsprung weight on the trailerís axle. You can go without springs, but especially if your planning build the trailer as light as possible, you may see fatigue issues over time.

Try to design for stability. Every trailer will sway at some speed, even properly loaded ones. Well designed trailers will sway at speeds higher than you will ever reach. Making a compact trailer (short) will make it more squirrely than a longer one. Think of a grandfather clock pendulum. The longer the pendulum is the slower it sways side to side. The shorter it is the faster it will sway. Also remember the tow rig will enter into the stability equation.

Looks like your tow rig has ok wheelbase, it is relatively heavy, and has stiff sidewall tires (if they are the stock ones anyway), but that long rear overhang is going to work against you. It will give the trailer more leverage to push the back end of the van around during cornering or during sway conditions. As others have suggested, a weight distributing hitch with sway control would probably be a good idea.

Its cool to see all the different ideas. If the majority of your towing will be at highway speeds, then, as others have already said, aerodynamics will have a much greater impact than anything else. Since everything consists of engineering compromises, make reducing drag a priority over reducing weight.

The security of four tires is nice and the dual wheel setup appears to be a good alternative to a tandem axle setup. Anybody have thoughts why dualys wouldnít be a good compromise?

Springs or no springs? With no springs the unsprung weight will be huge. Hit a large bump and without springs to absorb the impact energy you will see much higher peak loads and stresses to the trailer structure. Remember you will have to add the trail rigís unsprung weight (tires, rims, axles, and parts of the suspension) to the trailer weight to get the total unsprung weight on the trailerís axle. You can go without springs, but especially if your planning build the trailer as light as possible, you may see fatigue issues over time.

Try to design for stability. Every trailer will sway at some speed, even properly loaded ones. Well designed trailers will sway at speeds higher than you will ever reach. Making a compact trailer (short) will make it more squirrely than a longer one. Think of a grandfather clock pendulum. The longer the pendulum is the slower it sways side to side. The shorter it is the faster it will sway. Also remember the tow rig will enter into the stability equation.

Looks like your tow rig has ok wheelbase, it is relatively heavy, and has stiff sidewall tires (if they are the stock ones anyway), but that long rear overhang is going to work against you. It will give the trailer more leverage to push the back end of the van around during cornering or during sway conditions. As others have suggested, a weight distributing hitch with sway control would probably be a good idea.

All great points.
The over hang on the van is part of the issue it greatly degrades the tow capacity of the van to 7000llbs (I realize thats enough for my situation)just trying to keep the load low, stable and light weight. I also don't want to have to change gears in the van to pull the trailer. It has 3.50s in the axle.Goes nice down the e way with out a load, kinda want to keep it that way.

To me this number isn't worth it. Based on a different thread, it appears that very few tow more than 5K per year. So, a $150 per year savings is all you will net. In return, you need to be very consious of how you are loaded. Yes, I realize that $150 is significant, but like so many other discussions, if you are compromised by $150 per year, you are probably in the wrong sport.

A round trip to Canada is 600 miles, or $15. Make or break? I don't think so.

I find it odd that so many disregard my comments when I have actually done this. And with a reasonably light vehicle. Although I don't have pics of the other trailer, I actually had 2 different single axle trailers. Neither one worked well. But, at that time I didn't have a weight distributing hitch so balancing was super critical. I agree that with a WDH the balancing is not quite so sensitive.

If someone does this, I hope you have good success. But, at this time, I haven't read anything that there is significant savings or a good reason for it.

Lowering CG? Like Hagggar, I don't support a deck over trailer but rather a drop axle design. So, to lower your CG lower than that requires a more complex design that is likely to drag in many situations. I don't think that scrubbing around corners has a very significant effect on mileage. Also, most of us put a tool box on the front for straps, jack, spare stuff, etc. Now load this box up one time & don't the next and your dedicated mounting configuration is compromised.

Yes, 2 extra tires will impact mileage. I wonder how much it is. This may be your biggest savings.

As mentioned, wind resistance is the other big issue. But, when talking about jeeps, they are not very aerodynamic no matter how low you get them.

Since the concensus is to reduce weight and lower COG, does anyone have data to compare flat towing a specific vehicle versus putting it on a trailer? This would be a good indicator. Take your trail rig and flat tow it. Then stick it on a tandem trailer & check the mileage again. Since you are taking a vehicle on 4 tires and loading it onto a trailer with 4 tires, your difference would be COG and weight.

Since the concensus is to reduce weight and lower COG, does anyone have data to compare flat towing a specific vehicle versus putting it on a trailer? This would be a good indicator. Take your trail rig and flat tow it. Then stick it on a tandem trailer & check the mileage again. Since you are taking a vehicle on 4 tires and loading it onto a trailer with 4 tires, your difference would be COG and weight.

My suspicion is very little change.

BTW, what makes you think you will save 1 mpg?

get me a trailer

actually flat towing the samurai with the liberty, i get about 14-15 mpg, i'd suspect with the addition of a trailer (probably coming close to Doubling the weight, I'd get 10-12 mpg and have a hell of a time moving it up hills.

I don't think Aerodynamics and COG play a big role in towing mileage (open trailers) because neither vehicle is aerodynamic enough to matter. Weight is probably the biggest killer, then coupled with speed. There are probably enough people with similar trucks to prove/disprove this

i could get 20 mpg flat towing the samurai with my sonoma at 55-60 mph, but at 70-75 that would drop to 16 mpg.

My advice, Get as small of trailer as you can and drive slow, remember its okay if a prius passes you

Since the concensus is to reduce weight and lower COG, does anyone have data to compare flat towing a specific vehicle versus putting it on a trailer? This would be a good indicator. Take your trail rig and flat tow it. Then stick it on a tandem trailer & check the mileage again. Since you are taking a vehicle on 4 tires and loading it onto a trailer with 4 tires, your difference would be COG and weight.

My suspicion is very little change.

BTW, what makes you think you will save 1 mpg?

I've done this with my Tahoe. Generally I flat tow as I don't have a trailer but I have also used tandem axle trailers on more than one occasion. Flat Towing, I can expect to get about 12 mpg. I've gotten higher but not since I put boggers on my Jeep. i think the best I got was 14 but that's very unusual. Using a trailer, I expect to get 10 mpg. I've dragged my Jeep to Virginia on one, to OSTC on a different one and partway home from drummond on a third and 10 was the magic number each time. I also notice the load alot less Flat Towing too. But that's a 1500lb weight savings vs. a few hundred too.

One thing I'm surprised hasn't been mentioned and maybe it's cuz the pics have dual rear wheels but I would never want to tow that much weight on a single axle, single wheeled trailer. Imagine how it would pull during a blowout. At least with a dually style axle you won't be completely out. As a unusual thought though, how about running an 8 lug axle and then using H1 rims with run flats as a precaution....

Speed kills mpg because of aerodynamic drag. There are enough posts on different web sites where guys with enclosed trailers that say there is not much difference whether they run lightly loaded or heavy. They canít all be full of crap, can they? This shows that aerodynamic drag has a more significant effect than weight (with in reason) when lots of highway miles are involved. And an open trailer with a trail rig would be dirtier aerodynamically, so mpg will be reduced even more from going faster.

Flat towing should give better mpg, unless there are serious losses due to the towed rigís driveline friction or tire rolling resistance (or tweaked toe settings, /-\ lol). A flat towed vehicle is tucked in nice and tight to the tow rig, the perfect drafting. Put the towed vehicle on a trailer further back from the tow rig and higher up as well and yeah the aerodynamics will make a huge difference. Again this is assuming we all have a significant amount of highway miles to travel to get to the wheeling spots.

I not sure I understand the concern over single axle. Maybe a single axle just needs a good trailer design and is less forgiving to improper loading? I have a single axle deck over with wood sides that weighs 2k empty. Iíve towed it on many trips, with a few different trucks, from a couple miles to over 600 miles, one time full of logs, another time a pump and motor that weighed around 4,500 lbs, all sorts of crap over the years and never had an issue. All plain weight carrying (no WDH). Granted the cog of those loads were somewhat lower than a trail rig, but one could easily design a deck to bring the cog of a trail rig to the same height. What am I not getting?

A lot of good points pointing about the difference between flat towing & trailering. I guess my test idea was a little too simple.

Regarding my concern or what you are missing: Have you ever loaded a rig on a tandem trailer & started down the road & had it start to sway? Stop, move it forward 6-8" and it trailers fine? This is because you balanced it properly & got the proper tongue weight.

With a single axle trailer, it is much much harder to get this balance just right.

A question further back asked what's the difference between a buggie, boat & jeep. Both the buggie and boat have the majority of their weight almost directly over the axle allowing differences in loading to be insignificant. I don't know the exact number but I would guess 60-70% More in many cases. Let's run with that number for a minute. Figure a buggie at 70/30 and a jeep at 50/50 and both are both 100 inch wheel base. A buggie weighs in at 2000 pounds so it would place 600 pounds of tongue weight. (assuming being measured directly under the front tires) A jeep weighs in at 4000 pounds (minimum) and would place 2000 pounds of tongue weight.

I'm sitting here early in the morning & not going to lay this out exact so give me a little latitude here. but move the buggie back 5 inches which is 5%. Now your weight at the front tires is 500 pounds..... an 8.3% change.
Do the same thing with the jeep & it changes to 1800 pounds... a 9% change. Percentage wise it doesn't sound like much but it doubles the difference in tongue weight. (the buggie changes 100 pounds and the jeep changes 200 pounds)

So, if you are trying to tow with your light duty SUV and only wanted 200 pounds of tongue weight, +/- 5" goes from double your desired tongue weight to none at all. Now throw in differences of having your spare on or not, 20 gallons of gas or empty (120 pounds), tools, etc, you effect it greatly. Yes, you should be able to place your rig within an inch or 2 all the time.

Again guys, I'm not saying it can't be done. I'm saying I've done it and it wasn't all that simple. The best way I figured out how to do it was determine the desired settle on the trailer hitch. Say 2". I carried a tape measure with me & would measure the unloaded tongue height. Then I would load up and place my jeep on the trailer till the tongue dropped the desired amount.

I think if you can move up to the next class of vehicle to tow with, it would be worth it. Parents Yukon netted 14mpg towing to Canada. My Suburban is 8mpg. But I can't tow down to KY, TN with the Yukon cuz the hills absolutely kill it, I was about 9mpg and still 8mpg with the Suburban. Shave some pounds, reduce a bit of wind drag, maybe tire drag, you could probably get the Yukon to go through KY without running it to its limit. And that would be totally worth it for me. Their Yukon nets around 17+mpg hwy unloaded and my suburban is 10mpg.

I remember towing our quads with a single axle. It was a bit of a PITA to balance it just right. Especially when I towed with my Cherokee, it was picky about tongue weight...

Balance, for the most part, woudl be a design issue, not a day-to-day thing, IMO.

If you are taking the time to BUILD a trailer like this, then have your rig weighed(without driver) on each axle, as you would load it. A little math and a bathroom scale or two can do the rest.

My design thughts would be that there are 4 pockets for the tires, so there is no chance of the thing being in the wrong place.

I can see with quads and snowmobiles how it'd be hard to get the balance right. But if you have no variability in where you place the tires, then its going to be the same every time, unless you change your rig.

Again, its a specialized setup for someone willing to do it right, not for the average guy.

this is probably the coolest of the trailers, but one thing I could see being a pain is if your rig is broken trying to get it on the trailer to get it home.

I do like the idea of keeping the rig low. One thing I have seen with towing my jeep is a slight difference (~1mpg) in towing mileage when pulling with my windshield down or off. I think keeping the rig tucked in behind the tow rig would help mileage.

And if your rig is not going to change much. When I run the dunes I don't have my spare tire, carrier, tools, etc on the back. Trail ready adds an additional 300 pounds.

Correct. But, if you look at what you could either place some of that stuff in the truck, instead of the trailer (tool bags, for example) or, say, place the spare tire in front of the Jeep to balance the weight in the back.

I think this setup only makes sense if you have a rig under 4000lbs loaded, though, and closer to 3 than 4. Geos, light CJs, buggies, that kind of thing. For those cases, saving 800-1000lbs makes a bigger difference, than when you've got something thats 5500lbs + 2000lb trailer.

Correct. But, if you look at what you could either place some of that stuff in the truck, instead of the trailer (tool bags, for example) or, say, place the spare tire in front of the Jeep to balance the weight in the back.

I think this setup only makes sense if you have a rig under 4000lbs loaded, though, and closer to 3 than 4. Geos, light CJs, buggies, that kind of thing. For those cases, saving 800-1000lbs makes a bigger difference, than when you've got something thats 5500lbs + 2000lb trailer.

Yup, and these differences in numbers can be dictated with the load rating of the tire and trailer spindle. That is the big advantage of the dually setup.

this is probably the coolest of the trailers, but one thing I could see being a pain is if your rig is broken trying to get it on the trailer to get it home.

I do like the idea of keeping the rig low. One thing I have seen with towing my jeep is a slight difference (~1mpg) in towing mileage when pulling with my windshield down or off. I think keeping the rig tucked in behind the tow rig would help mileage.

Liked it as well .I was thinking if I did that but back on ,then the wieght would be more over the axle

I think the height of the towed vehicle on the trailer is much more of a factor than a bit of weight. Now in my case, comparing a tandem car hauler (2100 lb) to a single axle utility trailer (900 lb), both carrying a 2600 lb samurai, the weight does make a difference. But in most people's cases, with larger rigs on the trailer, the weight of the trailer will not make as much of a difference.

Now to aero, I can tow my Tbird (3900 lb) on my car hauler (2100 lb) and a couple of mpg's more than towing my Samurai (2600 lb). Towing 1300 lbs more, that is no higher than the roof of my truck, is much easier on the truck, than the lighter load that the hood is level with my roof of the tow vehicle. Stop and go, the weight makes more of a difference, but at highway speeds, the aero is the larger factor.